1. Field of the Invention
The present invention relates to a lateral electric field type liquid crystal display device which exhibits an excellent characteristic in the viewing angle property.
2. Description of the Related Art
While the widely used TN (Twisted Nematic) system can provide high contrast, there is also an issue that the visual angle dependency thereof is tremendous since the liquid crystal molecule axes are raised by the perpendicular electric field. Recently, there is a strong demand to acquire same picture qualities from any directions with large-scaled monitors of TV (television sets) as well as portable information terminals. In order to fulfill such demand, it has become popular to employ systems such as the IPS (In-plane Switching) and the FFS (Fringe field Switching), with which the liquid crystal is rotated in a plane that is almost in parallel to the substrate by applying a lateral electric field that is substantially in parallel to the substrate.
Those lateral electric field systems rotate the molecule axes of the nematic liquid crystal aligned horizontally within a plane that is in parallel to the substrate by using the lateral electric field. With the lateral electric field systems, it is possible to suppress changes in the picture quality caused depending on the viewing angle directions according to the rise of the liquid crystal molecule axes. Therefore, the viewing angle property can be improved.
In those liquid crystal display devices using the lateral electric field, Japanese Unexamined Patent Publication Hei 10-307295 (Patent Document 1) discloses a technique which suppresses coloring in two regions through disposing the two regions where the comb-like electrodes for generating the lateral electric fields are set to be orthogonal to each other and providing the two regions where the initial alignment directions of the liquid crystal are set to be orthogonal by corresponding thereto.
Further, Japanese Unexamined Patent Publication 2011-27886 (Patent Document 2) discloses a technique which, between the pixels, sets the pixel display region and the region between the pixels to be in different alignment states. However, there is no indication regarding a technique for stabilizing the alignment between the orthogonal alignment regions regarding the pixel divided into two orthogonal alignment regions described later in this Specification.
However, when the alignment directions of the liquid crystal within the pixel are set to be orthogonal to each other for improving the viewing angle, there may be cases where the alignment becomes unstable in the boundary between the two regions where the alignment directions are orthogonal to each other.
It is therefore an exemplary object of the present invention to provide a lateral electric field type liquid crystal display device with a structure that includes, within a pixel, two regions where the initial alignment directions of the liquid crystal are orthogonal to each other, which is excellent in the display uniformity and is capable of providing a stable display even for external disturbances such as finger pressures or the like by stabilizing the alignment direction in the boundary between those two regions.